Engine starting mechanism



S. GILBERT ENGINE STARTING MECHANISM Aug. 5, 1941.

Filed Jan. 27, 1940 .INVENTOR.

Patented Aug. 5, 1941 ENGINE STARTING MECHANISM: Samuel Gilbert, Verona,N. J assignor to Bendix poration of Delaware Aviation Corporation, SouthBend,

Ind., a cor- ApplicationiJanuary 27, 1940, SerialNo. 316,021

7 Claims. (01. 192-54) This invention relates to engine startingmechanism, and particularly to starting mechanism adapted to impartinitial rotary movement to a rotatable part of the engine to be started,yet mechanically separate therefrom during normal running of the engine.

An object of the invention is to provide a starting device in which theestablishment of driving connection with the engine is direct, immediateand positive, yet characterized. by an absence'of any considerableamount of shock to the parts, and also by an absence of any substantialamount of energy dissipation.

Another object is to provide a starting device in which overloading ofthe starting motor is prevented by the inherent tendency of the drivingconnection to yield whenthe torque exceeds the limit value; there being,however, no yielding parts other than the engine engaging parts, andsaid parts being automatically withdrawn to po-v sitions of completeseparation from the rotating engine parts, at theend of the enginestartingcycle, wherefore normal running of the engine does not involvethe rotation therewith of any engine starter parts.

These and other objects of the invention will become apparent frominspection of the following specification when read with reference tothe accompanying drawing wherein is illustrated the preferred embodimentofthe'invention. It is to be-expressly understood, however, that thedraw ing is for the purpose of illustration only, and is not designed asa definition of the limits of the invention, reference being had toappended claims for this purpose.

In the drawing 7 Fig. 1 is a combined sectional, elevation anddiagrammatic view' of a device embodying the invention;

Fig. 2 is a longitudinal sectional view of the engine engaging elementsand certain associated parts on a slightly larger scale than shown inFig. 1;

Fig. 3 is a transverse sectional view along the line 3-3 of Fig. 2; and

Fig. 4 is a view similar to Fig. 3 but with the elements in thepositions occupied during transfor of starting torque to the enginemember.

Inv this drawing the invention isshown applied to the starting of aninternal combustion engine having a flanged rotatable element 5 providedwith threads or equivalent means 6 for attachment of the enginecrankshaft or some crankshaft connected element, and further having a Icylindrical rim 1 integral with the flanged portion 8 to form a drumwhose inner cylindrical surface is adapted to be engaged by radially movable shoes, herein shown in the form of semi-cylindrical segments II andI2 having circumferential grooveswhich togetherform a circular channelfor reception of av toroidalspring l3 having sufficient tension tonormally hold the engine engaging elements H and 12 in the non-engagingpositions indicated in Figs. 1 and 3, but insuiiioient. to preventmovement of said segments into driving engagement with the inner surfaceof the drum. 1 in response to operation of the engaging meanshereinafter described.

The driving. means of'the starter is shown in Fig. 1 as involving anelectric motorcontained in a casing l6 forming one part of the sectionalhousing of the starter and attachable to the adjoining section IT. bysuitable means as indicated at l8; the starter section i! being in turnsupported. upon the mounting flange l 9 of the engine crankcase by meansof the through-bolts 2! which couple the flange 22 of the section 11 tothe said mounting flange IS. The armature shaft 23 of the motor is shownas having an extending portion Z lpiloted, with the aid of the frictionreducing sleeve 25, withinthe' socketed portion 26 of" a. member 21.whichdrivably connects the planet pinions 2,8 of-a planetary gear trainwith the engine engaging shoes II and I2. Theconnection of the member 21with the planet pinions 28 takes the form-of a flanged portion 29 whichserves as acarrier for the shafts3l on which the. pinions 28aremoun'ted, there being preferably three of such pinions spaced atequal annular intervals aboutjthe axis of the stationary, internallytoothed orbit gear32 With which said pinions ar e in mesh, although onlyone of the three pinions of the group is actually shown in Fig. 1.Associated with planets '28 is a second set of planets 33correspondingly spaced and also in mesh with the teeth of the orbit gear32, although only one of'this group of pinions'33 appears in Fig. 1. AY-shaped plate serves to space the pinions 33 fromthe pinions 28, and isprovided with openings to receive the hubstfi which also extend throughthepinions 33' and constitute mounting means, in conjunction with theplate 34, for thesaid pinions 33. Cooperating with pinions 33 and 28,respectively, are sun gears 31 and 38,. the former being shown as anintegral part. of the extended portion 240i the armature shaft 23, whilethe sun gear 33 is ,rotatably mounted on the bearing sleeve 25heretofore referred to, and is integral with plate 34. The sun gears 31and 38 therefore complete the planetary system for converting therotation of armature shaft 23 into rotation of the member 2'! at reducedspeed. Member 21 has a reduced end 4| engaging shoes II and I2 wherebyrotation of member 21 produces corresponding rotation of saidengine-engaging shoes II and I2.

The means for moving the shoes I I and I2 into torque-transmittingengagement with the engine member I involves the reduced end portion 4|of the transmission member 21, also a plurality of radially extendingpins 42 passing through radial openings in said reduced portion 4|, anda longitudinally shiftable rod 43 extending into the bore 44 (Fig. 2) insaid member 4|; said rod 43 having a tapered end adapted to pass betweenthe inner ends of the pins 42 in cam fashion, to exert a radially actingforce upon the segments II and I2 through the intermediate blocks 48 and49 against which the tapered ends of the pins 42 bear, said blocks beingin turn received in recesses formed in the shoes I and I2, as shown.

It will be seen that the cross-section of the reduced portion 4| of thetransmission member includes two parallel sides and 52 having planesurfaces, said sides being joined by two camsurfaced sides 53 and 54whose curvature is such as to increase the radially exerted pressure,and hence the torque-transmitting capacity, of the engine-engaging shoesII and I2 in response to rotation of the motor-driven transmissionmember 21 (and its reduced end portion 4|) in the direction of thearrows shown in Figs. 3 and 4; the said radially acting pressure beingcaused by the cam action of the surfaces 53 and 54 against the shoes IIand I2, respectively, and being subsequently relaxed only by, and in theevent of, a superior turning effort or overrunning of the engine memberI with respect to the said shoes II and I2. When such an overrunningoccurs the shoes II and I2 are first advanced angularly beyond the zonesof greatest cam pressure thereupon (the said zones being indicateddiagrammatically at A and B in Fig. 4), after which action the toroidalspring I3 becomes effective to return the shoes II and I2 to theirnormal (disengaged) positions as indicated in Figs. 1 and 3.

The means whereby the control of the longitudinal shifting of the rod 43is synchronized with the initial rotation of the transmission member 21(and hence with the camming action of the reduced portion 4| thereof) isshown as involving an electromagnetic device including a winding 6|energizable from a suitable source of current 62 adapted to supplycurrent to both the solenoid winding EI and the motor windings inresponse to closure of the manually controlled switch 64 and theelectromagnetically controlled switch 66, the latter being normally heldout of engagement with the contacts 61 and 68 by reason of the action ofthe coiled compression spring 69 upon collar II of the rod 43. Rod 43has a magnetic portion 12, also a portion 13 of nonconducting material,the latter including a collar I4 bearing against the switch element 66to hold it normally in the position indicated in Fig. 1. From thecontact element 68 there extends a conductor TI leading to the terminalelement I8 to which is attached one side of the motor windings, theopposite side thereof being grounded (by any suitable connection, not

shown) for completion of the return circuit to the battery.

With the arrangement described it will be apparent that closure of theswitch 64 will result in energization of the winding BI and hence amagnetic influence upon the portion I2 of rod 43, sufficient to causethe said rod 43 to move to the right against the yielding opposition ofthe spring 69. The same action causes a movement of the switch element66 into bridging relationship with the contacts 61 and 68, theconstruction shown being such that the rod 43 may follow through tocomplete the radial shifting of the pins 42, even though further forwardmovement of the switch 66 is prevented by reason of its abutment againstthe contacts 61 and 68 with which it cooperates electrically, andagainst which it continues to be urged as long as the solenoid winding6| remains energized, due to the action of compression spring 8| whoseouter end abuts the head 82 of the rod 43 and whose inner end bears uponthe switch member 66; it being understood that the latter is looselycarried on the rod 43 whereby relative longitudinal movement can occurbetween the two.

The engagement of the member 66 with the contacts 61 and 68 completesthe circuit to the motor windings simultaneously with the completion ofthe inward shift of the rod 43, whereby rotary effort is applied to thegear train and transmission member 2! to produce the abovedescribedcamming action of the surfaces 53 and 54 against the shoes II and I2simultaneously with completion of the radial movement thereof, asinduced by the action of the tapered end of the rod 43 upon the pins 42.A driving connection of limited torque transmitting capacity the amountof which will depend upon the extent of contact area and the materials'of which the shoes II and I2 are constructed, as well as upon thestrength of the opposition offered by spring I3 is thereby established,and initial rotary movement is accordingly imparted to the engine member5.

Aided by this initial rotary movement, the concurrent commencement ofcombustion in the engine cylinders serves to produce an acceleration ofthe engine member 5 beyond the cranking speed of the shoes II and I2,whereupon the latter are automatically disengaged as above described.The operator may then re-open the switch 64 to de-energize theelectromagnet 6| and the motor, thus permitting spring 69 to becomeeffective upon collar II of the rod 43 to return the latter to itsnormal position (Fig. 2), in which position the pins 42 are likewisefree to return, thereby removing all opposition to the performance bythe spring I3 of its function of maintaining the shoes II and I2 in thewithdrawn position with respect to the engine member I during the entirerunning period of the engine.

What I claim is:

1. In an. engine starting apparatus, the combination withengine-engaging friction shoes, of means including a rod extending intothe apparatus for moving said friction shoes to engineengaging position,means for driving said friction shoes, said driving means beingoperative, upon movement of said friction shoes to engine-engagingposition, to increase the frictional, torque transmitting pressureexerted by said friction shoes, and means for producing movement of saiddriving means only when the shift of said friction shoes to engineengaging position has been completed.

2. In an engine starting apparatus, the combination with anengine-engaging friction shoe, of means including a rod extending intothe apparatus for moving said friction shoe to engineengaging position,means for driving said friction shoe, said driving means including a camelement engaging said friction shoe and operative, upon movement of saidfriction shoe to engineengaging position, to increase the frictional,torque transmitting pressure exerted by said friction shoe, and meansfor producing movement of said cam element only when the shift of saidfriction shoes to engine engaging position has been completed.

3. In an engine starting apparatus, the combination with a rotatableengine-engaging member, of means including a rod movable along the axisof rotation of said engine-engaging member, for moving saidengine-engaging member radially of said axis, to engine-engagingposition, and means for driving said engine-engaging member, saiddriving means including a cam-surfaced element mounted between androtatable about the same axis as said engine engaging member, and

.operative, upon movement of said engine-engaging member toengine-engaging position, to rotate to a limited degree in relation tosaid engineengaging member and thereby increase the torque transmittingpressure exerted by said engineengaging member.

4. In an engine starting apparatus, the combination of a rotatableengine-engaging member,

of means for moving said engine-engaging member radially of its axis ofrotation, to engineengaging position, means for driving saidengineengaging member, said driving means being operthe shift of saidengine engaging member to engine engaging position has been completed.

5. In an engine starting apparatus, the combination with engine engagingfriction shoes, of rotatable cam-surfaced means for driving said shoes,and means including pins shiftable radially of, and slidable looselywithin, said cam-surfaced means, for initially moving said frictionshoes to engine engaging position.

6. In an engine starting apparatus, the combination with engine engagingfriction shoes, of rotatable cam-surfaced means for driving said shoes,and means including pins shiftable radially of, and slidable looselywithin, said cam-surfaced means, for initially moving said frictionshoes to engine engaging position, said cam-surfaced means acting, uponmovement of said friction shoes to engine engaging position, to increasethe torque transmitting pressure exerted by said friction shoes.

'7. In an engine starting apparatus, the combination with engineengaging friction shoes, of means including a rod and radially movableblocks actuated by said rod (said blocks being engageable with saidfriction shoes) for moving said friction shoes to engine engagingposition, and means occupying space between said radially movable blocksto drive said friction shoes, said driving means being operative, uponmovement of said radially movable blocks, to increase the frictionaltorque transmitting pressure exerted by said friction shoes.

SAMUEL GILBERT.

